This invention relates generally to a lubricating composition for finishing synthetic textile fibers, and in particular to a composition containing a silahydrocarbon oil and an improved emulsifier having a polyoxyalkylene chain and a hydrophobic component having a plurality of C.sub.4 -C.sub.32 aliphatic groups.
Synthetic polymers are made into fibers in the form of continuous filaments, usually by a process of melt spinning. The filaments are cooled and converted into filament yarn, staple or tow. Typically, a lubricant composition or finish is applied to the fibers to aid in processing operations by reducing friction, dissipating static charges and modifying the pliability and yarn bundle forming characteristics of the fibers. The finish should be relatively no-absorbent, since this can adversely affect the strength and elasticity of the fibers. Also, as the finish is absorbed, the fibers tends to swell, lubrication is lost and friction increases. Another requirement of the finish is that it should be removable from the fiber by conventional procedures.
Mineral oil was one of the first compositions used as a fiber finish for synthetic fibers. However, due to the high degree of absorption of mineral oil into some fibers, especially elastomeric polyurethanes, mineral oils have been replaced by polysiloxane oils.
The polysiloxane oils provide better lubrication and are generally absorbed less by the fibers. In particular, polysiloxane oils have been useful in conjunction with polymers that are especially sensitive to the deleterious effects of absorption of lubricants, such as elastomeric polyurethane (spandex) fibers. Although polysiloxane oils have been used on elastomeric polyurethanes for well over twenty years, there are several drawbacks associated with the processing of fibers treated with these oils. The polysiloxane oils do not offer the cohesion needed to keep yarn bundles or packages together, and package degradation is noticed with time. The lack of boundary friction associated with the polysiloxane oils also leads to irregularities in yarn package formation, such as saddling and bulging, and limits yarn package size.
Safety and environmental concerns also militate against the use of polysiloxane oils as fiber finishes. Beam drippings of the polysiloxane on the floors of processing plants creates an environment ripe for slipping accidents. This danger is exacerbated by the difficulty of removing polysiloxane oils from the floor. Environmentally, the polysiloxane oils have come under attack in that the oils do not readily biodegrade. Furthermore, since the polysiloxane oils tend to propagate a flame, oil which remains on the yarn after fabric formation can significantly increase the flammability of fabric. Thus, the use of polysiloxane oils by the textile industry is coming under increased regulation.
A silahydrocarbon lubricant for textile fibers is disclosed by Plonsker, U.S. Pat. No. 4,932,976. Plonsker suggests that the lubricant may be provided as an emulsion. However, suitable emulsifiers are not disclosed.
A polyalphaolefin based fiber finish and useful emulsifiers are disclosed in Ross et al., U.S. Pat. No. 4,995,884. The patent discloses a finish composition comprising from 30 to 70 wt. % of a polyalphaolefin, 25 to 50 wt. % of an emulsifier and 5 to 20 wt. % of an antistatic agent. Specific examples of finish formulations having from 37.6 to 56.6 wt. % polyalphaolefin are provided in the patent. The finish composition is applied to the fiber as an aqueous emulsion. Any suitable emulsifying agent may be used and several commercially available emulsifiers are recommended.
Seemuth, U.S. Pat. No. 4,999,120 discloses a finish for spandex fibers which is an aqueous emulsion of a polydimethylsiloxane lubricant and an ethoxylated, long-chained alkanol emulsifier. The solids portion of the emulsion contains from 80% to 99.5% polydimethylsiloxane.
While it is often desirable to provide a finish as an emulsion from the viewpoint of ease of application and removal from the textile fiber, emulsifiers generally have a negative impact on performance of the lubricant. Additionally, the emulsifier may absorb into the textile fiber resulting in swelling and wakening of the fiber. Thus, selection of an emulsifier is critical to the performance of a finish composition.